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MAGNETIC 

PHENOMENA  AROUND  DEEP 
BORINGS. 

BY  A.  C.  LANE,  STATE  GEOLOGIST. 

[Reprinted  from  the  Fourth  Report  of  the  Michigan  Academy  of  Science,  1904.] 


166 


MICHIGAN  ACADEMY  OF  SCIENCE. 


MAGNETIC  PHENOMENA  AROUND  DEEP  BORINGS. 

BY  A.  C.  LANE,  STATE  GEOLOGIST. 

In  an  early  paper  by  Prof.  Alexander  Winchell  he  calls  attention  to 
magnetic  phenomena  around  certain  springs  in  the  State,  but  without 
specifying  precisely  what  these  phenomena  were.  It  is  also  noteworthy 
that  a large  number  of  the  springs  or  rather  artesian  wells,  that  have 
been  exploited  as  mineral  waters,  have  “magnetic”  in  their  name*  or  like 
the  St.  Louis  spring  make  reference  in  their  circulars  to  their  magnetic 
powers  as  of  great  value.  In  the  course  of  my  studies  on  the  water 
supply  of  Michigan,  and  in  the  examination  of  other  borings  of  various 
kinds,  which  is  part  of  my  regular  business,  it  became  a matter  of  some 
interest  to  know  just  what  these  magnetic  phenomena  were.  So  far  as  I 
could  find  out  they  were  of  two  kinds.  All  the  wells  in  question  are 
drilled  wells  in  iron  casing,  and  even  when  this  casing  was  said  to  be 
wrought  or  soft  iron  it  had  a considerable  attraction.  It  would  for  in- 
stance hold  out  nails,  and  the  pull  upon  a wrench  could  very 
readily  be  felt.  Sometimes  too,  it  was  noticed  that  the  blade  of  a 
knife  immersed  in  the  water  also  became  magnetic.  Of  this  last  state- 
ment I may  remark  that  while  it  is  very  easy  for  knife  blades  to  have 
become  magnetic  without  the  owner’s  knowledge  yet  there  is  no  reason 
to  doubt  that  in  some  cases  knife  blades  did  really  become  magnetic. 
However,  I do  not  know  of  any  case  where  the  knife  blade  became  magnetic 
except  as  it  was  held  in  the  water  as  it  flowed  from  the  casing,  and  hence 
close  to  the  latter.  Now  any  knife  blade  being  steel  if  it  is  held  close  to  a 
magnet  will  soon  become  permanently  magnetized  itself,  so  that  the  two 
phenomena  reduce  themselves  to  one,  mainly  the  magnetism  of  the  casing. 
As  to  any  well  defined  magnetic  effects  of  the  waters  of  a medical  nature 
I am  not  qualified  to  judge,  not  being  a physician,  nor  have  I had  them 
stated  to  me  in  any  tangible  state.  Now  in  regard  to  the  casing,  we  must 
remember  that  the  earth  as  a whole  is  a magnet  and  electro-magnetic  cur- 
rents are  continually  flowing  in  it,  and  that  any  iron  rod  or  tube  lying 
in  a magnetic  field  and  cutting  the  lines  of  force  will  itself  be  magnetized, 
just  as  a soft  iron  nail  touching  or  close  to  a magnet  will  itself  become 
attractive  and  be  able  to  draw  a smaller  nail.  Applying  this  to  the  case 
of  these  deep  wells  we  have  continuous  lines  of  iron  pipes,  of  wrought 
iron  or  steel  (and  sometimes  pipe  that  is  sold  for  wrought  iron  is  really 
steel),  which  may  vary  in  length  from  a hundred  feet  to  two  or  three 
thousand  or  more  and  it  is  not  surprising  xthat  they  should  be  magnetic 
as  they  cut  *a  good  many  lines  of  force  of  the  great  earth  magnet.  These 
lines  are  represented  in  a horizontal  direction  by  the  compass  and  in  a 
vertical  plane  by  the  dip  needle.  If  this  explanation  of  the  magnetism 
is  correct,  then  all  strings  of  casing  should  prove  to  be  more  or  less 
magnetic.  Such  indeed  I have  found  to  be  the  case  very  often  to  the 
considerable  surprise  of  the  owners  thereof,  though  well  drillers  tell  me 


* Such  as  Midland  Magnetic,  Grand  Rapids  Magnetic,  Riverside  Magnetic  at  Detroit,  and  Magnetic 
Springs  at  Leslie,  Lansing,  Fruitport  and  Huboardston,  the  analyses  of  which  are  given  in  Water 
Supply  Paper  No.  31  of  the  U.  S.  Geological  Survey. 


LANE  ON  MAGNETIC  PHENOMENA. 


167 


that  they  know  this  to  be  the  rule.  This  magnetic  force  is  sometimes 
very  considerable.  It  will  often  hold  out  the  largest  size  of  spike,  and 
I believe  in  the  case  of  the  well  over  five  thousand  feet  deep,  tested  by 
Prof.  William  Hallock  of  Columbia  Univrsity,  it  could  hold  a wrench.  I 
have  found  that  in  lowering  a thermometer  down  these  wells  the  steel  tape 
clung  to  the  sides  so  that  it  made  a material  difference  in  the  energy  re- 
quired to  handle  it.  It  was  just  about  as  much  as  a man  could  do  to 
start  2,600  feet  of  steel  tape  from  the  Grayling  well,  although  the  weight 
of  the  tape  itself  would  not  be  over  25  pounds.  Again  in  measuring  the 
depth  of  a well  recently  sunk  at  Cheboygan,  2,700  feet  deep  or  more,  Mr. 
Rust  the  driller,  informed  me  that  the  magnetic  drag  on  the  tape  was 
such  that  it  was  also  impossible  to  tell  when  the  20  pound  weight  was  at 
the  bottom.  At  the  same  time  it  seems  to  me  that  the  magnetism  is  not 
directly  proportional  to  the  depth  of  the  hole  alone,  although  the  larger 
and  deeper  holes  are  of  course  in  a general  way  more  magnetic,  and  I 
should  think  there  might  be  interesting  opportunity  for  some  student  of 
geophysics  to  make  some  magnetic  observations  of  considerable  interest. 
The  university  of  Michigan  has  for  instance  put  down  recently  a well 
dome  1,300  feet  deep,  which  at  one  time,  if  not  at  present,  was  cased  over 
a thousand  feet.  It  would  seem  that  here  might  be  a good  chapce  for 
careful  experiment.  I should  be  very  glad  to  have  any  suggestions  from 
students  of  physics  as  to  how  observations  upon  these  phenomena  could 
be  made  more  definite  and  instructive.  Before  closing  I would  like  to 
mention  another  phenomenon  though  it  does  not  occur  in  a deep  boring 
* but  in  a deep  shaft.  The  Tamarack  mine  has  recently  sunk  a shaft  (No. 
5),  which  goes  vertically  downward  some  4,666  feet  before  it  encounters 
the  lode  which  the  mine  is  working.  In  preparing  to  connect  this  with  the 
old  workings  of  the  mine  two  plumb  bobs  or  pendulums  were  let  down  the 
shaft  4,250  feet,  and  whereas  they  were  17.58,  or  at  another  time  16.33, 
feet  apart  at  the  top,  they  were  found  to  be  17.65  respectively  16.42  feet 
apart  at  the  bottom.  In  No.  2 shaft  the  divergence  was  from  12.6  feet  at 
the  top  to  12.7  feet  at  the  bottom.  This  divergence  was  unexpected,  but 
Prof.  W.  Hallock  of  Columbia  who  has  investigated  the  matter,  concludes 
that  it  is  a phenomenon  of  a character  similar  to  those  we  have  described 
that  the  long  wires  in  the  magnetic  field  of  the  earth  were  magnetized,  so 
that  the  similar  poles  repelled  each  other  as  they  always  do.  He  adds, 
“I  may  say  that,  as  far  as  the  magnetizing  influence  of  the  earth  upon 
the  casings  is  concerned,  it  would  matter  but  little  whether  the  pipes  were 
really  wrought  iron  or  steel,  because,  inasmuch  as  they  remain  in  the 
magnetic  field,  they  would  of  course  remain  magnetized,  even  if  they 
were  soft  wrought  iron. 

“ A factor  which  probably  influences  the  strength  of  the  magnetism  of 
these  casings  is  the  number  of  strings  that  may  be  put  into  any  particular 
well.  In  the  well  at  Wheeling  there  were,  I believe  four  strings,  the 
longest  one  being  something  over  1,500  feet.  In  that  well  it  proved  im- 
possible to  sink  a steel  tape  through  the  casing,  even  with  a 50  pound 
weight  attached  to  the  lower  end  of  it.  In  my  temperature  observations 
a steel  wire  was  used  which  of  course  adhered  to  the  walls  of  the  well  but 
little.” 

Farther  investigation  at  the  Tamarack  Mine  by  President  McNair 
showed  that  the  phenomenon  there  was  mainly  due  to  the  draft  of  air. 


